An elastic membrane and carrier head for chemical mechanical polishing

Abstract

This invention discloses an elastic membrane and a bearing head for chemical mechanical polishing. The elastic membrane includes: a base plate; an upright portion extending vertically upward along the outer edge of the base plate; a first extension and a second extension extending from the inner side of the upright portion toward the center, the second extension being located above the first extension and extending from the upper end of the upright portion, the two extending from the upright portion together forming a first chamber; the outer surface of the upright portion is provided with an unloading groove to counteract the bending moment generated by the deformation of the second extension due to the pressure applied to the first chamber.

Description

Technical Field

[0001] This invention belongs to the field of chemical mechanical polishing technology, and more specifically, relates to an elastic membrane and a bearing head for chemical mechanical polishing. Background Technology

[0002] The integrated circuit industry is the core of the information technology industry, playing a crucial role in promoting the digital and intelligent transformation and upgrading of the manufacturing industry. Chips are the carriers of integrated circuits, and chip manufacturing involves processes such as integrated circuit design, wafer fabrication, wafer processing, electrical measurement, dicing, packaging, and testing. Among these, chemical mechanical polishing (CMP) is one of the five core processes in wafer fabrication.

[0003] Chemical mechanical polishing (CMP) is an ultra-precision surface processing technology that achieves global planarization. During CMP, the wafer is typically held against the bottom surface of a support head, with the side of the wafer having the deposited layer abutting against the upper surface of the polishing pad. The support head rotates in the same direction as the polishing pad under the actuation of the drive assembly, applying a downward load to the wafer. Polishing fluid is supplied to the upper surface of the polishing pad and distributed between the wafer and the polishing pad, allowing the wafer to complete the CMP process under the combined action of chemicals and machinery.

[0004] The elastic diaphragm is a key component of the bearing head, which mounts the back side of the wafer to be polished and applies load from above. To ensure the accuracy of the polishing load application, rigid inner and / or outer rings need to be configured on the wall of the elastic diaphragm.

[0005] During the polishing process, the wafer and the elastic film rotate relative to each other. Rigid components such as the inner ring and outer ring will indirectly contact the wafer, causing stress damage such as scratches on the back of the wafer. This is not conducive to ensuring the polishing quality of the wafer.

[0006] Especially for third-generation semiconductor materials such as silicon carbide, although they have advantages such as wider bandgap, higher thermal conductivity, higher breakdown field strength, higher saturated electron drift velocity, and higher bonding energy, their material hardness is relatively high, requiring high-pressure polishing to remove the material from the surface of third-generation semiconductors. Therefore, when using existing elastic films and carrier heads for chemical mechanical polishing, defects such as mechanical scratches on the back of the wafer will occur. Summary of the Invention

[0007] This invention provides an elastic membrane and a support head for chemical mechanical polishing, aiming to at least solve one of the technical problems existing in the prior art.

[0008] A first aspect of the present invention provides an elastic membrane for chemical mechanical polishing, comprising:

[0009] Base plate;

[0010] The upright portion extends vertically upwards along the outer edge of the base plate.

[0011] The first extension and the second extension extend from the inside of the upright portion toward the center. The second extension is located above the first extension and extends from the upper end of the upright portion. Together with the upright portion, they form the first chamber.

[0012] The outer surface of the upright part is provided with a load-bearing groove to counteract the bending moment generated by the deformation of the second extension caused by the pressurization of the first chamber.

[0013] In some embodiments, the unloading groove is an annular structure and is arranged circumferentially along the upright portion.

[0014] In some embodiments, the unloading groove is located below the first extension.

[0015] In some embodiments, the unloading groove is located above the midpoint of the vertical height of the corresponding upright portion of the second chamber, and the second chamber is a chamber formed by the first extension portion, the upright portion and the bottom plate portion.

[0016] In some embodiments, the unloading groove is an outwardly facing opening groove, which includes a first wall surface, a transition surface and a second wall surface. The first wall surface extends upward and inward, the transition surface is located between the first wall surface and the second wall surface, and the second wall surface extends outward from the end of the transition surface.

[0017] In some embodiments, the first wall extends upward at an angle of 40-75° to the base plate.

[0018] In some embodiments, the second wall surface is located below the first extension.

[0019] In some embodiments, the horizontal distance by which the unloading groove extends inward is less than or equal to half the wall thickness of the corresponding upright portion.

[0020] In some embodiments, the wall thickness of the upright portion of the second chamber is greater than the wall thickness of the base plate portion.

[0021] In some embodiments, the wall thickness of the upright portion of the first chamber is less than the wall thickness of the upright portion of the second chamber.

[0022] A second aspect of the present invention provides a carrier head, comprising:

[0023] Carrier plate;

[0024] The elastic membrane described above is disposed below the carrier disk to hold the wafer to be polished.

[0025] A third aspect of the present invention provides a polishing apparatus, which includes a polishing disc, a dressing device, a liquid supply unit, and the aforementioned bearing head. The bearing head is equipped with an elastic membrane having an unloading groove to counteract the bending moment caused by chamber pressure deformation and to adjust the material removal rate at the wafer edge.

[0026] The beneficial effects of this invention include:

[0027] a. The upright portion of the elastic membrane is provided with an unloading groove to counteract the bending moment generated by the deformation of the second extension caused by the pressurization and expansion of the first chamber, thereby reducing or controlling uncontrollable factors of the polishing load and improving the uniformity of the polished wafer.

[0028] b. The upright portion of the elastic film is thickened to remove the rigid support rings originally installed on the inner and outer sides of the upright portion, so as to avoid indirect contact between the support rings and the wafer, which would cause white spot defects on the back side of the wafer.

[0029] c. An unloading groove is provided on the outer side of the thickened upright part so that the elastic membrane expands within a safe range, avoiding excessive expansion of the elastic membrane and abutting against the inner wall of the retaining ring;

[0030] d. The unloading tank is located away from the bottom plate of the elastic membrane to prevent contaminants such as polishing waste liquid from entering the unloading tank and crystallizing, which would affect the offsetting of the bending moment caused by expansion deformation;

[0031] e. The internal structure of the unloading groove and its connection with the upright part are transitioned by a rounded arc to avoid stress concentration that could affect the application of polishing load;

[0032] f. The wall thickness of the upper first upright part is less than the wall thickness of the lower second upright part, so that the pressurized and expanded first chamber can normally transmit the polishing load along the second upright part;

[0033] g. The cross-sectional shape of the unloading groove is a circular arc groove, so that after the elastic membrane is pressurized and expanded, the unloading groove itself will not form a stack, thereby avoiding the accumulation and crystallization of pollutants such as polishing waste liquid inside the unloading groove;

[0034] h. The unloading groove is located above the horizontal center line of the second upright part and below the first extension part to prevent the unloading groove from affecting the pressurization and expansion of the first chamber and the second chamber;

[0035] i. The upright section is made of hard rubber to ensure the normal transmission of polishing loads even when the rigid support ring is removed. Attached Figure Description

[0036] The advantages of the present invention will become clearer and easier to understand through the following detailed description in conjunction with the accompanying drawings, which are merely illustrative and do not limit the scope of protection of the present invention, wherein:

[0037] Figure 1 This is a schematic diagram of an elastic membrane for chemical mechanical polishing provided in an embodiment of the present invention;

[0038] Figure 2 yes Figure 1 A magnified view of a section at point A in the middle;

[0039] Figure 3 This is a schematic diagram of a bearing head provided in an embodiment of the present invention;

[0040] Figure 4 yes Figure 3 A magnified view of a section at point B in the middle;

[0041] Figure 5 yes Figure 4 A schematic diagram of the elastic deformation of the first chamber of the elastic membrane after being pressurized in the embodiment;

[0042] Figure 6a This is a schematic diagram of an elastic membrane installed at the lower part of a bearing head according to an embodiment of the present invention;

[0043] Figure 6b This is a schematic diagram of an elastic membrane installed at the lower part of a bearing head according to another embodiment of the present invention;

[0044] Figure 6c This is a schematic diagram of an elastic membrane installed at the lower part of a bearing head according to another embodiment of the present invention;

[0045] Figure 7 yes Figure 6c A schematic diagram of the deformation of the first chamber of the medium elastic membrane after pressure is applied;

[0046] Figure 8 This is a schematic diagram of a polishing apparatus provided in an embodiment of the present invention. Detailed Implementation

[0047] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0048] The accompanying drawings in this specification are schematic diagrams used to illustrate the concept of the invention and to schematically show the shapes of the various parts and their interrelationships. It should be understood that, in order to clearly show the structure of the various components of the embodiments of the invention, the drawings are not drawn to the same scale, and the same reference numerals are used to indicate the same parts in the drawings.

[0049] In this invention, "Chemical Mechanical Polishing (CMP)" is also called "Chemical Mechanical Planarization (CMP)," and a wafer (W) is also called a substrate (Substrate), with equivalent meanings and practical functions. The term "comprising" and similar expressions should be understood as open-ended inclusion, i.e., "including but not limited to." The term "based on" should be understood as "at least partially based on." The term "one embodiment" or "this embodiment" should be understood as "at least one embodiment." The terms "first," "second," etc., may refer to different or the same objects and are used only to distinguish the objects referred to, without implying a specific spatial order, temporal order, order of importance, etc., of the objects referred to. In some embodiments, values, processes, selected items, determined items, equipment, apparatus, means, parts, components, etc., are referred to as "best," "lowest," "highest," "minimum," "maximum," etc. It should be understood that such descriptions are intended to indicate that selection can be made from a number of available functional options, and that such selection is not necessarily better, lower, higher, smaller, larger, or otherwise preferred in any other aspect or all aspects than other options.

[0050] Figure 1 This is a schematic diagram of an elastic membrane 100 for chemical mechanical polishing according to an embodiment of the present invention. The elastic membrane 100 includes:

[0051] The base plate 10 has a disk-shaped structure, and the wafer to be polished is mounted below the base plate 10;

[0052] The upright portion 20 has a ring-shaped structure and extends vertically upward along the outer edge of the base plate portion 10;

[0053] A first extension 30 and a second extension 40 extend from the inside of the upright portion 20 toward the center; wherein the second extension 40 is located above the first extension 30 and extends from the upper end of the upright portion 20 toward the center of the elastic membrane 100.

[0054] First extension 30, second extension 40, upright section 20 and Figure 3 The first pressure ring 230 shown encloses to form the first chamber C1, the first extension 30, the upright portion 20 and Figure 3 The second pressure ring 240 shown encloses and forms the second chamber C2. In order to distinguish the upright portions 20 corresponding to the first chamber C1 and the second chamber C2, the portion corresponding to the first chamber C1 is referred to as the first upright portion 21, and the portion corresponding to the second chamber C2 is referred to as the second upright portion 22.

[0055] During chemical mechanical polishing, the elastic membrane 100 needs to be installed on... Figure 3 The bearing head 200 is shown below the bearing disk 210 and pressurized towards the first chamber C1 and the second chamber C2 to apply a polishing load to the wafer below the elastic membrane 100.

[0056] Figure 2 yes Figure 1 A partial enlarged view at point A shows that an unloading groove 50 is provided on the outer side of the upright part 20. Specifically, the unloading groove 50 is provided on the outer side of the second upright part 22.

[0057] The unloading groove 50 configured on the elastic membrane 100 has at least the following functions: First, the unloading groove 50 can counteract the bending moment M generated by the deformation of the second extension 40 due to the pressurization of the first chamber C1. Figure 5 (As shown), the elastic membrane 100 applies a load to the wafer edge region, thereby adjusting the material removal rate of the wafer edge region; secondly, the unloading groove 50 can control the deformation of the second extension 40, preventing the expansion of the first chamber C1 or the second chamber C2 from contacting the wafer edge region. Figure 3 The inner wall of the retaining ring 220 shown abuts against the elastic membrane 100, thereby ensuring the application of load.

[0058] In this invention, the unloading groove 50 is an annular structure, which is arranged circumferentially along the upright portion 20. That is, the unloading groove 50 is arranged circumferentially through the upright portion 20 to uniformly adjust the polishing load in the circumferential direction of the elastic membrane 100. In other words, the load applied by the elastic membrane 100 to the back side of the wafer is reduced to prevent the material removal rate in the wafer edge area from being too high and affecting the polishing uniformity.

[0059] In one embodiment of the present invention, the unloading groove 50 is located below the first extension 30 to suppress excessive deformation caused by pressurization of the elastic membrane 100 chamber. In the present invention, during chemical mechanical polishing, the elastic membrane 100 is mounted on the bearing head 200, and there is no need to configure rigid support rings on the inner and outer sides of the upright portion 20. The provision of the unloading groove 50 is beneficial to controlling the pressure deformation of the upright portion 20, so that the polishing load can be applied to the back side of the wafer through the first extension 30 and the upright portion 20. The elastic membrane 100 does not need to be equipped with rigid support rings, which can avoid indirect contact between rigid materials and the back side of the wafer, and prevent defects such as scratches on the back side of the wafer, such as "white spots" on the back side of the wafer.

[0060] In one embodiment of the present invention, the unloading groove 50 is located above the midpoint of the vertical height of the vertical part 20 corresponding to the second chamber C2. That is, the unloading groove 50 is located above the midpoint of the vertical height of the second vertical part 22. Figure 2 In the middle, the center line of the vertical height of the second upright part 22 is L, and the unloading groove 50 is located above the center line L.

[0061] Furthermore, the unloading groove 50 is located near the junction of the first extension 30 and the upright portion 20. After the first chamber C1 is pressurized and expanded, the second extension 40 bulges and elongates. The unloading groove 50 can counteract the bending moment generated by the pressurized deformation of the second extension 40, reducing the influence of the uncertainty of the pressurized expansion of the second extension 40 on the applied load. This allows the polishing load to be transferred to the back side of the wafer through the first extension 30 and the upright portion 20, thereby accurately adjusting the polishing load at the wafer edge.

[0062] In this invention, the unloading groove 50 is an outward-facing opening. Specifically, the unloading groove 50 includes a first wall surface 51, a transition surface 52, and a second wall surface 53. The first wall surface 51 extends upward and inward, while the transition surface 52 is located between the first wall surface 51 and the second wall surface 53. The second wall surface 53 extends outward from the end of the transition surface 52. In this invention, "inward extension" means extending towards the center of the elastic membrane 100, and "outward extension" means extending towards the outer side of the elastic membrane 100.

[0063] Furthermore, the first wall surface 51 extends upward at an angle, and the angle between the first wall surface 51 and the base plate portion 10 is 40-75°. Preferably, the angle between the first wall surface 51 and the base plate portion 10 is 50-60°, so that when the unloading groove 50 counteracts the bending moment, the second wall surface 53 will not come into contact with the first wall surface 51, thus ensuring a good counteracting effect. If the second wall surface 53 comes into contact with the first wall surface 51 when the unloading groove 50 counteracts the bending moment, the first wall surface 51 will react on the upper part of the unloading groove 50, thereby affecting the counteracting effect of the unloading groove 50.

[0064] Figure 2 In the illustrated embodiment, the second wall surface 53 is located below the first extension 30, so that the unloading groove 50 does not affect the load application to the first chamber C1 when performing moment cancellation. Specifically, the second wall surface 53 is disposed below the first extension 30 to prevent the unloading groove 50 from affecting the pressurized expansion of the first chamber C1 and thus affecting the normal application of the polishing load.

[0065] In this invention, the horizontal distance of the inward extension of the unloading groove 50 is D, and the wall thickness of the second upright portion 22 is T2. Therefore, the horizontal distance D of the inward extension of the unloading groove 50 is less than or equal to half of the wall thickness T2 of the second upright portion 22. This arrangement of the unloading groove 50 helps to ensure the normal transmission of the polishing load applied through the upright portion 20 and prevents the unloading groove 50 from causing excessive deformation of the upright portion 20, which would affect the application of the load.

[0066] Meanwhile, by setting the unloading tank 50 in this way, it is possible to suppress or reduce the accumulation of pollutants such as polishing waste liquid inside the unloading tank 50, so as to avoid surface crystallization or mutual adhesion between the first wall surface 51 and the second wall surface 53, which would affect the normal loading of the elastic membrane 100.

[0067] In one embodiment of the present invention, the wall thickness of the second chamber C2 corresponding to the upright portion 20 is greater than the wall thickness of the bottom plate portion 10, that is, the wall thickness T2 of the second upright portion 22 is greater than the wall thickness of the bottom plate portion 10. The thickened upright portion 20 can ensure its own strength, so that the elastic membrane 100 with the unloading groove 50 can expand within a safe range to ensure the normal application of polishing load.

[0068] Understandably, the thickened design of the upright portion 20 is intended to facilitate the removal of the rigid support ring. That is, after the rigid support ring of the elastic film 100 is removed, the thickened upright portion 20 can normally transmit the load towards the back side of the wafer to ensure the normal operation of the elastic film 100.

[0069] In some embodiments, the upright portion 20 is made of a rigid rubber material, such as chloroprene, ethylene propylene copolymer, etc., to ensure the structural strength of the upright portion 20 while avoiding scratching the back side of the wafer.

[0070] Furthermore, the upright portion 20 corresponding to the first chamber C1 is the first upright portion 21, and the wall thickness of the first upright portion 21 is denoted as T1; while the wall thickness of the upright portion 20 corresponding to the second chamber C2 is the wall thickness T2 of the second upright portion 22. In this invention, the wall thickness T1 of the first upright portion 21 is less than the wall thickness T2 of the second upright portion 22. This arrangement helps to ensure the elastic deformation of the first chamber C1 and the second chamber C2, and at the same time, the polishing load can be transferred to the edge region of the wafer through the upright portion 20 so as to better participate in the application of the polishing load; at the same time, removing the elastic membrane 100 of the rigid support ring can effectively prevent the support ring from making hard contact with the back of the wafer, avoiding scratch defects on the back of the wafer.

[0071] Figure 2In the process, the horizontal length of the first extension 30 is greater than the horizontal length of the second extension 40. The difference in their horizontal lengths determines the magnitude of the force transmitted from the first chamber C1 and / or the second chamber C2 to the area directly below the upright part 20 during the pressurization process. Specifically, the magnitude of the length difference between the first extension 30 and the second extension 40 is roughly proportional to the magnitude of the force transmitted to the area directly below the upright part 20.

[0072] A second aspect of the present invention provides a carrier head 200, the schematic diagram of which is shown below. Figure 3 As shown, the carrier head 200 includes a carrier disk 210 and the elastic membrane 100 described above, wherein the elastic membrane 100 is disposed below the carrier disk 210 to load the wafer to be polished.

[0073] Furthermore, the carrier head 200 also includes a retaining ring 220, which is disposed below the carrier disk 210 and located on the outer periphery of the elastic membrane 100 to prevent the wafer from sliding out of the interior of the carrier head 200 during the polishing process. At the same time, the retaining ring 220 participates in the application of polishing load so that the carrier head 200 can achieve multi-zone pressure regulation through the elastic membrane 100.

[0074] Figure 4 yes Figure 3 In the enlarged view at point B, the elastic membrane 100 is fixed below the carrier disk 210 by the first pressure ring 230 and the second pressure ring 240, and the wafer W to be polished is attracted to the bottom surface of the base plate portion 10 of the elastic membrane 100.

[0075] Specifically, the first pressure ring 230 presses against the lower part of the second extension 40 and is detachably connected to the support plate 210, so that the first upright part 21, the second extension 40, the first pressure ring 230 and the first extension 30 together form the first chamber C1; the second pressure ring 240 presses against the first extension 30 and is detachably connected to the support plate 210 and / or the first pressure ring 230, so that the second upright part 22, the first extension 30, the second pressure ring 240 and the bottom plate part 10 together form the second chamber C2.

[0076] The unloading groove 50 is disposed on the outer periphery of the second upright part 22 to counteract the bending moment M caused by the deformation of the chamber when the elastic membrane 100 applies a load to the wafer, thereby avoiding the influence of the uncertainty of the elastic deformation of the elastic membrane 100 on the application of the load.

[0077] Figure 5 yes Figure 4A schematic diagram of the elastic deformation of the first chamber C1 of the elastic membrane 100 after being pressurized in this embodiment. In this embodiment, the first chamber C1 of the elastic membrane 100 expands under pressure, and the second extension 40 and the first upright portion 21 expand and extend outward; the unloading groove 50 provided can offset the bending moment caused by the elastic deformation of the second extension 40, so that the polishing load of the first chamber C1 acting on the wafer edge is transmitted downward through the first extension 30 and the upright portion 20.

[0078] Meanwhile, the unloading groove 50 can control the degree of elastic deformation of the first chamber C1, so that the first upright part 21 will not come into contact with the inner wall of the retaining ring 200, thereby ensuring the normal transmission of polishing load.

[0079] Figure 6a A schematic diagram is shown of an elastic membrane 100 provided in an embodiment of the present invention installed below the support plate 210 of the support head 200. In this embodiment, the unloading groove 50 of the elastic membrane 100 is symmetrically arranged with respect to the horizontal center line. Specifically, the first wall surface 51 extends upward and inward at an incline to the transition surface 52 of the arc-shaped structure, and the second wall surface 53 extends upward and outward at an incline from the end of the transition surface 52. That is, the angle between the first wall surface 51 of the unloading groove 50 and the bottom plate portion 10 is equal to the angle between the second wall surface 53 and the bottom plate portion 10. Here, the angles between the first wall surface 51 and the second wall surface 53 and the bottom plate portion 10 are acute angles.

[0080] As one aspect of this embodiment, the angle between the first wall surface 51 and the bottom plate portion 10 is 10-30°, so as to both offset the bending moment generated by elastic deformation and prevent contaminants such as polishing waste liquid from accumulating inside the unloading tank 50.

[0081] Figure 6b This diagram illustrates an elastic membrane 100 provided in an embodiment of the present invention installed below a support plate 210 of a support head 200. In this embodiment, a first wall surface 51 and a second wall surface 53 extend horizontally along the thickness direction of the upright portion 20, while a transition surface 52 is a vertical surface and connects the first wall surface 51 and the second wall surface 53.

[0082] To avoid stress concentration caused by deformation of the elastic membrane 100, a circular arc transition is used between the first wall surface 51 and the vertical transition surface 52, and between the second wall surface 53 and the vertical transition surface 52.

[0083] Meanwhile, the second wall surface 53 is located below the first extension 30 to suppress the influence of the unloading groove 50 on the first chamber C1.

[0084] Figure 6cThis diagram illustrates an embodiment of the present invention where an elastic membrane 100 is installed below a support plate 210 of a support head 200. In this embodiment, the unloading groove 50 has an arc-shaped structure and is symmetrically arranged above and below its horizontal center line. To avoid stress concentration in the elastic membrane 100, the unloading groove 50 and the outer wall of the upright portion 20 are connected by an arc.

[0085] Figure 7 yes Figure 6c A schematic diagram of the deformation of the first chamber C1 of the elastic membrane 100 after being pressurized. After the first chamber C1 is pressurized, the main pressure generated is transmitted downward through the first extension 30 and the upright part 20. At the same time, if the unloading groove 50 is not provided in the upright part 20, the second extension 40 is pressurized and bulges. The bending moment M generated by the deformation of the second extension 40 is transmitted to the edge of the wafer through the upright part 20.

[0086] Since the deformation of the second extension 40 caused by the pressure in the chamber is uncontrollable, the magnitude of the bending moment it generates is also undetermined. This makes it impossible to determine the load on the wafer edge caused by the bending moment generated by the pressure expansion of the second extension 40, which increases the difficulty of controlling the wafer edge pressure.

[0087] In this invention, the unloading groove 50 provided on the outer periphery of the upright portion 20 can offset the bending moment formed by the pressure expansion of the second extension portion 40, so that the bending moment generated by the pressure of the first chamber C1 is basically transmitted to the back side of the wafer through the first extension portion 30 and the upright portion 20, thereby improving the uniformity of wafer polishing.

[0088] At the same time, the unloading groove 50 can also prevent excessive deformation of the upright part 20 without a rigid support ring, so as to ensure the normal application of polishing load.

[0089] and Figure 5 Compared to the illustrated embodiments, Figure 7 In the embodiment, when the unloading groove 50 is offset by the polishing load, the upper end of the unloading groove 50 is far away from the inner side of the unloading groove 50, so as to avoid the stacking of the unloading groove 50 itself and the inability to offset the bending moment generated by the deformation of the second extension 40.

[0090] In addition, in this embodiment, the unloading tank 50 does not stack itself during the pressurization process of the elastic membrane 100, which can also prevent contaminants such as polishing waste liquid from accumulating and crystallizing inside the unloading tank 50, thereby preventing crystals from falling off and causing scratches on the wafer surface.

[0091] Furthermore, the present invention also provides a polishing apparatus 1000, the schematic diagram of which is shown below. Figure 8 As shown. The polishing equipment 1000 includes a polishing disc 300, a dressing device 400, a liquid supply unit 500, and the aforementioned support head 200.

[0092] Furthermore, a polishing pad is disposed above the polishing disc 300, and the polishing pad rotates together with the polishing disc 300; a horizontally movable support head 200 is disposed above the polishing pad, and the bottom of the support head 200 holds the wafer to be polished; a dresser 400 oscillates around a fixed point, and the dressing head disposed thereon rotates itself and applies a downward load to dress the surface of the polishing pad; a liquid supply unit 500 is disposed above the polishing pad to distribute the polishing liquid on the surface of the polishing pad.

[0093] During the polishing operation, the carrier head 200 presses the surface of the wafer to be polished against the surface of the polishing pad. The carrier head 200 rotates and reciprocates radially along the polishing disk 300, gradually removing the surface of the wafer in contact with the polishing pad. Simultaneously, the polishing disk 300 rotates, and the liquid supply unit 500 sprays polishing liquid onto the surface of the polishing pad. Under the chemical action of the polishing liquid, the relative movement between the carrier head 200 and the polishing disk 300 causes the wafer to rub against the polishing pad, thus achieving polishing.

[0094] The elastic diaphragm 100 of the bearing head 200 has an unloading groove 50 to counteract the bending moment caused by the pressure deformation of the chamber and adjust the material removal rate at the wafer edge. Furthermore, the wall thickness of the upright portion 20 of the elastic diaphragm 100 is increased to facilitate the removal of the rigid support rings clamped to the inner and outer sides of the upright portion 20, thereby preventing the rigid support rings from indirectly contacting the back of the wafer and forming scratches such as "white spots," thus improving the quality of wafer polishing by the bearing head 200.

[0095] It should be noted that the solution / equipment provided in this application is mainly used for chemical mechanical polishing of wafers made of third-generation semiconductor materials. Specifically, it can be used for 4-inch, 6-inch, or 8-inch wafers processed from third-generation semiconductor materials, such as 4-inch, 6-inch, or 8-inch GaN wafers, or 8-inch SiC wafers. Furthermore, the solution / equipment provided in this application can also be applied to the polishing of large silicon wafers.

[0096] In addition, due to the high difficulty in growing third-generation semiconductor materials, there are problems such as difficulty in controlling the temperature field, slow growth rate, high requirements for yield parameters, and difficulty in crystal diameter expansion. As a result, the wafer size of third-generation semiconductor materials is mainly 6-8 inches. With the development of technology and the overcoming of growth problems, the wafer size of third-generation semiconductor materials may expand to 12 inches or even larger. The solutions / equipment provided in this application are also applicable and are all within the protection scope of this application.

[0097] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An elastic film for chemical mechanical polishing, characterized by, include: Base plate; The upright portion extends vertically upwards along the outer edge of the base plate. The first extension and the second extension extend from the inside of the upright portion toward the center. The second extension is located above the first extension and extends from the upper end of the upright portion. Together with the upright portion, they form the first chamber. The outer side of the upright part is provided with a load-bearing groove to counteract the bending moment generated by the deformation of the second extension caused by the pressurization of the first chamber. The elastic membrane further includes a second chamber, which is formed by the first extension, the upright portion and the bottom plate portion; the unloading groove is located above the midpoint of the vertical height of the corresponding upright portion of the second chamber; The wall thickness of the upright part of the second chamber is greater than the wall thickness of the bottom plate, and the wall thickness of the upright part of the first chamber is less than the wall thickness of the upright part of the second chamber.

2. The elastic film of claim 1, wherein, The unloading groove is an annular structure and is arranged circumferentially along the upright part.

3. The elastic membrane as described in claim 1, characterized in that, The unloading groove is located below the first extension.

4. The elastic membrane as described in claim 1, characterized in that, The unloading groove is an outward-facing open groove, which includes a first wall surface, a transition surface, and a second wall surface. The first wall surface extends upward and inward, the transition surface is located between the first wall surface and the second wall surface, and the second wall surface extends outward from the end of the transition surface.

5. The elastic membrane as described in claim 4, characterized in that, The first wall extends upward at an angle of 40-75° with the bottom plate.

6. The elastic membrane as described in claim 4, characterized in that, The second wall surface is located below the first extension.

7. The elastic membrane as described in claim 4, characterized in that, The horizontal distance inwardly extending from the unloading groove is less than or equal to half the wall thickness of the corresponding upright part.

8. A bearing head, characterized in that, include: Carrier plate; The elastic membrane according to any one of claims 1 to 7 is disposed below the support disk for loading the wafer to be polished.

9. A polishing equipment, characterized in that, It includes a polishing disc, a dressing device, a liquid supply unit, and a bearing head as described in claim 8, wherein the bearing head is equipped with an elastic membrane having an unloading groove to counteract the bending moment caused by chamber pressure deformation and adjust the material removal rate at the wafer edge.

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